using System;
using System.Data;
using System.Xml;
using System.Data.OleDb;
using System.Collections;


	/// <summary>
	/// The OleDbHelper class is intended to encapsulate high performance, scalable best practices for 
	/// common uses of OleDbClient.
	/// </summary>
public sealed class OleDbHelper
{
    #region private utility methods & constructors

    //Since this class provides only static methods, make the default constructor private to prevent 
    //instances from being created with "new OleDbHelper()".
    private OleDbHelper() { }

    /// <summary>
    /// This method is used to attach array's of OleDbParameters to an OleDbCommand.
    /// 
    /// This method will assign a value of DbNull to any parameter with a direction of
    /// InputOutput and a value of null.  
    /// 
    /// This behavior will prevent default values from being used, but
    /// this will be the less common case than an intended pure output parameter (derived as InputOutput)
    /// where the user provided no input value.
    /// </summary>
    /// <param name="command">The command to which the parameters will be added</param>
    /// <param name="commandParameters">an array of OleDbParameters tho be added to command</param>
    private static void AttachParameters(OleDbCommand command, OleDbParameter[] commandParameters)
    {
        foreach (OleDbParameter p in commandParameters)
        {
            //check for derived output value with no value assigned
            if ((p.Direction == ParameterDirection.InputOutput) && (p.Value == null))
            {
                p.Value = DBNull.Value;
            }

            command.Parameters.Add(p);
        }
    }

    /// <summary>
    /// This method assigns an array of values to an array of OleDbParameters.
    /// </summary>
    /// <param name="commandParameters">array of OleDbParameters to be assigned values</param>
    /// <param name="parameterValues">array of objects holding the values to be assigned</param>
    private static void AssignParameterValues(OleDbParameter[] commandParameters, object[] parameterValues)
    {
        if ((commandParameters == null) || (parameterValues == null))
        {
            //do nothing if we get no data
            return;
        }

        // we must have the same number of values as we pave parameters to put them in
        if (commandParameters.Length != parameterValues.Length)
        {
            throw new ArgumentException("Parameter count does not match Parameter Value count.");
        }

        //iterate through the OleDbParameters, assigning the values from the corresponding position in the 
        //value array
        for (int i = 0, j = commandParameters.Length; i < j; i++)
        {
            commandParameters[i].Value = parameterValues[i];
        }
    }

    /// <summary>
    /// This method opens (if necessary) and assigns a connection, transaction, command type and parameters 
    /// to the provided command.
    /// </summary>
    /// <param name="command">the OleDbCommand to be prepared</param>
    /// <param name="connection">a valid OleDbConnection, on which to execute this command</param>
    /// <param name="transaction">a valid OleDbTransaction, or 'null'</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or PL/SQL command</param> 
    /// <param name="commandParameters">an array of OleDbParameters to be associated with the command or 'null' if no parameters are required</param>
    private static void PrepareCommand(OleDbCommand command, OleDbConnection connection, OleDbTransaction transaction, CommandType commandType, string commandText, OleDbParameter[] commandParameters)
    {
        //if the provided connection is not open, we will open it
        if (connection.State != ConnectionState.Open)
        {
            connection.Open();
        }

        //associate the connection with the command
        command.Connection = connection;

        //set the command text (stored procedure name or OleDb statement)
        command.CommandText = commandText;

        //if we were provided a transaction, assign it.
        if (transaction != null)
        {
            command.Transaction = transaction;
        }

        //set the command type
        command.CommandType = commandType;

        //attach the command parameters if they are provided
        if (commandParameters != null)
        {
            AttachParameters(command, commandParameters);
        }

        return;
    }


    #endregion private utility methods & constructors

    #region ExecuteNonQuery

    /// <summary>
    /// Execute an OleDbCommand (that returns no resultset and takes no parameters) against the database specified in 
    /// the connection string. 
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders");
    /// </remarks>
    /// <param name="connectionString">a valid connection string for an OleDbConnection</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or PL/SQL command</param>  
    /// <returns>an int representing the number of rows affected by the command</returns>
    public static int ExecuteNonQuery(string connectionString, CommandType commandType, string commandText)
    {
        //pass through the call providing null for the set of OleDbParameters
        return ExecuteNonQuery(connectionString, commandType, commandText, (OleDbParameter[])null);
    }

    /// <summary>
    /// Execute an OleDbCommand (that returns no resultset) against the database specified in the connection string 
    /// using the provided parameters.
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new OleDbParameter("@prodid", 24));
    /// </remarks>
    /// <param name="connectionString">a valid connection string for a OleDbConnection</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or PL/SQL command</param>  
    /// <param name="commandParameters">an array of OleDbParameters used to execute the command</param>
    /// <returns>an int representing the number of rows affected by the command</returns>
    public static int ExecuteNonQuery(string connectionString, CommandType commandType, string commandText, params OleDbParameter[] commandParameters)
    {
        //create & open an OleDbConnection, and dispose of it after we are done.
        using (OleDbConnection cn = new OleDbConnection(connectionString))
        {
            cn.Open();

            //call the overload that takes a connection in place of the connection string
            return ExecuteNonQuery(cn, commandType, commandText, commandParameters);
        }
    }

    /// <summary>
    /// Execute a stored procedure via an OleDbCommand (that returns no resultset) against the database specified in 
    /// the connection string using the provided parameter values.  This method will query the database to discover the parameters for the 
    /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
    /// </summary>
    /// <remarks>
    /// This method provides no access to output parameters or the stored procedure's return value parameter.
    /// 
    /// e.g.:  
    ///  int result = ExecuteNonQuery(connString, "PublishOrders", 24, 36);
    /// </remarks>
    /// <param name="connectionString">a valid connection string for a OleDbConnection</param>
    /// <param name="spName">the name of the stored prcedure</param>
    /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
    /// <returns>an int representing the number of rows affected by the command</returns>
    public static int ExecuteNonQuery(string connectionString, string spName, params object[] parameterValues)
    {
        //if we got parameter values, we need to figure out where they go
        if ((parameterValues != null) && (parameterValues.Length > 0))
        {
            //pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)
            OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet(connectionString, spName);

            //assign the provided values to these parameters based on parameter order
            AssignParameterValues(commandParameters, parameterValues);

            //call the overload that takes an array of OleDbParameters
            return ExecuteNonQuery(connectionString, CommandType.StoredProcedure, spName, commandParameters);
        }
        //otherwise we can just call the SP without params
        else
        {
            return ExecuteNonQuery(connectionString, CommandType.StoredProcedure, spName);
        }
    }

    /// <summary>
    /// Execute an OleDbDbCommand (that returns no resultset and takes no parameters) against the provided OleDbConnection. 
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  int result = ExecuteNonQuery(conn, CommandType.StoredProcedure, "PublishOrders");
    /// </remarks>
    /// <param name="connection">a valid OleDbConnection</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or PL/SQL command</param>
    /// <returns>an int representing the number of rows affected by the command</returns>
    public static int ExecuteNonQuery(OleDbConnection connection, CommandType commandType, string commandText)
    {
        //pass through the call providing null for the set of OleDbParameters
        return ExecuteNonQuery(connection, commandType, commandText, (OleDbParameter[])null);
    }

    /// <summary>
    /// Execute an OleDbCommand (that returns no resultset) against the specified OleDbConnection 
    /// using the provided parameters.
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  int result = ExecuteNonQuery(conn, CommandType.StoredProcedure, "PublishOrders", new OleDbParameter("@prodid", 24));
    /// </remarks>
    /// <param name="connection">a valid OleDbConnection</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or PL/SQL command</param>  
    /// <param name="commandParameters">an array of OleDbParamters used to execute the command</param>
    /// <returns>an int representing the number of rows affected by the command</returns>
    public static int ExecuteNonQuery(OleDbConnection connection, CommandType commandType, string commandText, params OleDbParameter[] commandParameters)
    {
        //create a command and prepare it for execution
        OleDbCommand cmd = new OleDbCommand();
        PrepareCommand(cmd, connection, (OleDbTransaction)null, commandType, commandText, commandParameters);

        //finally, execute the command.
        return cmd.ExecuteNonQuery();
    }

    /// <summary>
    /// Execute a stored procedure via an OleDbCommand (that returns no resultset) against the specified OleDbConnection 
    /// using the provided parameter values.  This method will query the database to discover the parameters for the 
    /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
    /// </summary>
    /// <remarks>
    /// This method provides no access to output parameters or the stored procedure's return value parameter.
    /// 
    /// e.g.:  
    ///  int result = ExecuteNonQuery(conn, "PublishOrders", 24, 36);
    /// </remarks>
    /// <param name="connection">a valid OleDbConnection</param>
    /// <param name="spName">the name of the stored prcedure</param>
    /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
    /// <returns>an int representing the number of rows affected by the command</returns>
    public static int ExecuteNonQuery(OleDbConnection connection, string spName, params object[] parameterValues)
    {
        //if we got parameter values, we need to figure out where they go
        if ((parameterValues != null) && (parameterValues.Length > 0))
        {
            //pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)
            OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet(connection.ConnectionString, spName);

            //assign the provided values to these parameters based on parameter order
            AssignParameterValues(commandParameters, parameterValues);

            //call the overload that takes an array of OleDbParameters
            return ExecuteNonQuery(connection, CommandType.StoredProcedure, spName, commandParameters);
        }
        //otherwise we can just call the SP without params
        else
        {
            return ExecuteNonQuery(connection, CommandType.StoredProcedure, spName);
        }
    }

    /// <summary>
    /// Execute an OleDbCommand (that returns no resultset and takes no parameters) against the provided OleDbTransaction. 
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  int result = ExecuteNonQuery(trans, CommandType.StoredProcedure, "PublishOrders");
    /// </remarks>
    /// <param name="transaction">a valid OleDbTransaction</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or PL/SQL command</param>  
    /// <returns>an int representing the number of rows affected by the command</returns>
    public static int ExecuteNonQuery(OleDbTransaction transaction, CommandType commandType, string commandText)
    {
        //pass through the call providing null for the set of OleDbParameters
        return ExecuteNonQuery(transaction, commandType, commandText, (OleDbParameter[])null);
    }

    /// <summary>
    /// Execute an OleDbCommand (that returns no resultset) against the specified OleDbTransaction
    /// using the provided parameters.
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  int result = ExecuteNonQuery(trans, CommandType.StoredProcedure, "GetOrders", new OleDbParameter("@prodid", 24));
    /// </remarks>
    /// <param name="transaction">a valid OleDbTransaction</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or PL/SQL command</param>  
    /// <param name="commandParameters">an array of OleDbParamters used to execute the command</param>
    /// <returns>an int representing the number of rows affected by the command</returns>
    public static int ExecuteNonQuery(OleDbTransaction transaction, CommandType commandType, string commandText, params OleDbParameter[] commandParameters)
    {
        //create a command and prepare it for execution
        OleDbCommand cmd = new OleDbCommand();
        PrepareCommand(cmd, transaction.Connection, transaction, commandType, commandText, commandParameters);

        //finally, execute the command.
        return cmd.ExecuteNonQuery();
    }

    /// <summary>
    /// Execute a stored procedure via an OleDbCommand (that returns no resultset) against the specified 
    /// OleDbTransaction using the provided parameter values.  This method will query the database to discover the parameters for the 
    /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
    /// </summary>
    /// <remarks>
    /// This method provides no access to output parameters or the stored procedure's return value parameter.
    /// 
    /// e.g.:  
    ///  int result = ExecuteNonQuery(conn, trans, "PublishOrders", 24, 36);
    /// </remarks>
    /// <param name="transaction">a valid OleDbTransaction</param>
    /// <param name="spName">the name of the stored procedure</param>
    /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
    /// <returns>an int representing the number of rows affected by the command</returns>
    public static int ExecuteNonQuery(OleDbTransaction transaction, string spName, params object[] parameterValues)
    {
        //if we got parameter values, we need to figure out where they go
        if ((parameterValues != null) && (parameterValues.Length > 0))
        {
            //pull the parameters for this stored procedure from the parameter cache (or discover them & populet the cache)
            OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet(transaction.Connection.ConnectionString, spName);

            //assign the provided values to these parameters based on parameter order
            AssignParameterValues(commandParameters, parameterValues);

            //call the overload that takes an array of OleDbParameters
            return ExecuteNonQuery(transaction, CommandType.StoredProcedure, spName, commandParameters);
        }
        //otherwise we can just call the SP without params
        else
        {
            return ExecuteNonQuery(transaction, CommandType.StoredProcedure, spName);
        }
    }

    #endregion ExecuteNonQuery

    #region ExecuteDataSet

    /// <summary>
    /// Execute an OleDbCommand (that returns a resultset and takes no parameters) against the database specified in 
    /// the connection string. 
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  DataSet ds = ExecuteDataset(connString, CommandType.StoredProcedure, "GetOrders");
    /// </remarks>
    /// <param name="connectionString">a valid connection string for an OleDbConnection</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or PL/SQL command</param>  
    /// <returns>a dataset containing the resultset generated by the command</returns>
    public static DataSet ExecuteDataset(string connectionString, CommandType commandType, string commandText)
    {
        //pass through the call providing null for the set of OleDbParameters
        return ExecuteDataset(connectionString, commandType, commandText, (OleDbParameter[])null);
    }

    /// <summary>
    /// Execute an OleDbCommand (that returns a resultset) against the database specified in the connection string 
    /// using the provided parameters.
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  DataSet ds = ExecuteDataset(connString, CommandType.StoredProcedure, "GetOrders", new OleDbParameter("@prodid", 24));
    /// </remarks>
    /// <param name="connectionString">a valid connection string for an OleDbConnection</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or PL/SQL command</param> 
    /// <param name="commandParameters">an array of OleDbParamters used to execute the command</param>
    /// <returns>a dataset containing the resultset generated by the command</returns>
    public static DataSet ExecuteDataset(string connectionString, CommandType commandType, string commandText, params OleDbParameter[] commandParameters)
    {
        //create & open an OleDbConnection, and dispose of it after we are done.
        using (OleDbConnection cn = new OleDbConnection(connectionString))
        {
            cn.Open();

            //call the overload that takes a connection in place of the connection string
            return ExecuteDataset(cn, commandType, commandText, commandParameters);
        }
    }

    /// <summary>
    /// Execute a stored procedure via an OleDbCommand (that returns a resultset) against the database specified in 
    /// the conneciton string using the provided parameter values.  This method will query the database to discover the parameters for the 
    /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
    /// </summary>
    /// <remarks>
    /// This method provides no access to output parameters or the stored procedure's return value parameter.
    /// 
    /// e.g.:  
    ///  DataSet ds = ExecuteDataset(connString, "GetOrders", 24, 36);
    /// </remarks>
    /// <param name="connectionString">a valid connection string for an OleDbConnection</param>
    /// <param name="spName">the name of the stored procedure</param>
    /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
    /// <returns>a dataset containing the resultset generated by the command</returns>
    public static DataSet ExecuteDataset(string connectionString, string spName, params object[] parameterValues)
    {
        //if we got parameter values, we need to figure out where they go
        if ((parameterValues != null) && (parameterValues.Length > 0))
        {
            //pull the parameters for this stored procedure from the parameter cache (or discover them & populet the cache)
            OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet(connectionString, spName);

            //assign the provided values to these parameters based on parameter order
            AssignParameterValues(commandParameters, parameterValues);

            //call the overload that takes an array of OleDbParameters
            return ExecuteDataset(connectionString, CommandType.StoredProcedure, spName, commandParameters);
        }
        //otherwise we can just call the SP without params
        else
        {
            return ExecuteDataset(connectionString, CommandType.StoredProcedure, spName);
        }
    }

    /// <summary>
    /// Execute an OleDbCommand (that returns a resultset and takes no parameters) against the provided OleDbConnection. 
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  DataSet ds = ExecuteDataset(conn, CommandType.StoredProcedure, "GetOrders");
    /// </remarks>
    /// <param name="connection">a valid OleDbConnection</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or PL/SQL command</param>
    /// <returns>a dataset containing the resultset generated by the command</returns>
    public static DataSet ExecuteDataset(OleDbConnection connection, CommandType commandType, string commandText)
    {
        //pass through the call providing null for the set of OleDbParameters
        return ExecuteDataset(connection, commandType, commandText, (OleDbParameter[])null);
    }

    /// <summary>
    /// Execute an OleDbCommand (that returns a resultset) against the specified OleDbConnection 
    /// using the provided parameters.
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  DataSet ds = ExecuteDataset(conn, CommandType.StoredProcedure, "GetOrders", new OleDbParameter("@prodid", 24));
    /// </remarks>
    /// <param name="connection">a valid OleDbConnection</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or PL/SQL command</param> 
    /// <param name="commandParameters">an array of OleDbParamters used to execute the command</param>
    /// <returns>a dataset containing the resultset generated by the command</returns>
    public static DataSet ExecuteDataset(OleDbConnection connection, CommandType commandType, string commandText, params OleDbParameter[] commandParameters)
    {
        //create a command and prepare it for execution
        OleDbCommand cmd = new OleDbCommand();
        PrepareCommand(cmd, connection, (OleDbTransaction)null, commandType, commandText, commandParameters);

        //create the DataAdapter & DataSet
        OleDbDataAdapter da = new OleDbDataAdapter(cmd);
        DataSet ds = new DataSet();

        //fill the DataSet using default values for DataTable names, etc.
        da.Fill(ds);

        //return the dataset
        return ds;
    }

    /// <summary>
    /// Execute a stored procedure via an OleDbCommand (that returns a resultset) against the specified OleDbConnection 
    /// using the provided parameter values.  This method will query the database to discover the parameters for the 
    /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
    /// </summary>
    /// <remarks>
    /// This method provides no access to output parameters or the stored procedure's return value parameter.
    /// 
    /// e.g.:  
    ///  DataSet ds = ExecuteDataset(conn, "GetOrders", 24, 36);
    /// </remarks>
    /// <param name="connection">a valid OleDbConnection</param>
    /// <param name="spName">the name of the stored prcedure</param>
    /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
    /// <returns>a dataset containing the resultset generated by the command</returns>
    public static DataSet ExecuteDataset(OleDbConnection connection, string spName, params object[] parameterValues)
    {
        //if we got parameter values, we need to figure out where they go
        if ((parameterValues != null) && (parameterValues.Length > 0))
        {
            //pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)
            OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet(connection.ConnectionString, spName);

            //assign the provided values to these parameters based on parameter order
            AssignParameterValues(commandParameters, parameterValues);

            //call the overload that takes an array of OleDbParameters
            return ExecuteDataset(connection, CommandType.StoredProcedure, spName, commandParameters);
        }
        //otherwise we can just call the SP without params
        else
        {
            return ExecuteDataset(connection, CommandType.StoredProcedure, spName);
        }
    }

    /// <summary>
    /// Execute an OleDbCommand (that returns a resultset and takes no parameters) against the provided OleDbTransaction. 
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  DataSet ds = ExecuteDataset(trans, CommandType.StoredProcedure, "GetOrders");
    /// </remarks>
    /// <param name="transaction">a valid OleDbTransaction</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or PL/SQL command</param> 
    /// <returns>a dataset containing the resultset generated by the command</returns>
    public static DataSet ExecuteDataset(OleDbTransaction transaction, CommandType commandType, string commandText)
    {
        //pass through the call providing null for the set of OleDbParameters
        return ExecuteDataset(transaction, commandType, commandText, (OleDbParameter[])null);
    }

    /// <summary>
    /// Execute an OleDbCommand (that returns a resultset) against the specified OleDbTransaction
    /// using the provided parameters.
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  DataSet ds = ExecuteDataset(trans, CommandType.StoredProcedure, "GetOrders", new OleDbParameter("@prodid", 24));
    /// </remarks>
    /// <param name="transaction">a valid OleDbTransaction</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or PL/SQL command</param> 
    /// <param name="commandParameters">an array of OleDbParamters used to execute the command</param>
    /// <returns>a dataset containing the resultset generated by the command</returns>
    public static DataSet ExecuteDataset(OleDbTransaction transaction, CommandType commandType, string commandText, params OleDbParameter[] commandParameters)
    {
        //create a command and prepare it for execution
        OleDbCommand cmd = new OleDbCommand();
        PrepareCommand(cmd, transaction.Connection, transaction, commandType, commandText, commandParameters);

        //create the DataAdapter & DataSet
        OleDbDataAdapter da = new OleDbDataAdapter(cmd);
        DataSet ds = new DataSet();

        //fill the DataSet using default values for DataTable names, etc.
        da.Fill(ds);

        //return the dataset
        return ds;
    }

    /// <summary>
    /// Execute a stored procedure via an OleDbCommand (that returns a resultset) against the specified 
    /// OleDbTransaction using the provided parameter values.  This method will query the database to discover the parameters for the 
    /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
    /// </summary>
    /// <remarks>
    /// This method provides no access to output parameters or the stored procedure's return value parameter.
    /// 
    /// e.g.:  
    ///  DataSet ds = ExecuteDataset(trans, "GetOrders", 24, 36);
    /// </remarks>
    /// <param name="transaction">a valid OleDbTransaction</param>
    /// <param name="spName">the name of the stored prcedure</param>
    /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
    /// <returns>a dataset containing the resultset generated by the command</returns>
    public static DataSet ExecuteDataset(OleDbTransaction transaction, string spName, params object[] parameterValues)
    {
        //if we got parameter values, we need to figure out where they go
        if ((parameterValues != null) && (parameterValues.Length > 0))
        {
            //pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)
            OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet(transaction.Connection.ConnectionString, spName);

            //assign the provided values to these parameters based on parameter order
            AssignParameterValues(commandParameters, parameterValues);

            //call the overload that takes an array of OleDbParameters
            return ExecuteDataset(transaction, CommandType.StoredProcedure, spName, commandParameters);
        }
        //otherwise we can just call the SP without params
        else
        {
            return ExecuteDataset(transaction, CommandType.StoredProcedure, spName);
        }
    }

    #endregion ExecuteDataSet

    #region ExecuteReader

    /// <summary>
    /// this enum is used to indicate weather the connection was provided by the caller, or created by OleDbHelper, so that
    /// we can set the appropriate CommandBehavior when calling ExecuteReader()
    /// </summary>
    private enum OleDbConnectionOwnership
    {
        /// <summary>Connection is owned and managed by OleDbHelper</summary>
        Internal,
        /// <summary>Connection is owned and managed by the caller</summary>
        External
    }

    /// <summary>
    /// Create and prepare an OleDbCommand, and call ExecuteReader with the appropriate CommandBehavior.
    /// </summary>
    /// <remarks>
    /// If we created and opened the connection, we want the connection to be closed when the DataReader is closed.
    /// 
    /// If the caller provided the connection, we want to leave it to them to manage.
    /// </remarks>
    /// <param name="connection">a valid OleDbConnection, on which to execute this command</param>
    /// <param name="transaction">a valid OleDbTransaction, or 'null'</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or PL/SQL command</param> 
    /// <param name="commandParameters">an array of OleDbParameters to be associated with the command or 'null' if no parameters are required</param>
    /// <param name="connectionOwnership">indicates whether the connection parameter was provided by the caller, or created by OleDbHelper</param>
    /// <returns>OleDbDataReader containing the results of the command</returns>
    private static OleDbDataReader ExecuteReader(OleDbConnection connection, OleDbTransaction transaction, CommandType commandType, string commandText, OleDbParameter[] commandParameters, OleDbConnectionOwnership connectionOwnership)
    {
        //create a command and prepare it for execution
        OleDbCommand cmd = new OleDbCommand();
        PrepareCommand(cmd, connection, transaction, commandType, commandText, commandParameters);

        //create a reader
        OleDbDataReader dr;

        // call ExecuteReader with the appropriate CommandBehavior
        if (connectionOwnership == OleDbConnectionOwnership.External)
        {
            dr = cmd.ExecuteReader();
        }
        else
        {
            dr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
        }

        return dr;
    }

    /// <summary>
    /// Execute an OleDbCommand (that returns a resultset and takes no parameters) against the database specified in 
    /// the connection string. 
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  OleDbDataReader dr = ExecuteReader(connString, CommandType.StoredProcedure, "GetOrders");
    /// </remarks>
    /// <param name="connectionString">a valid connection string for an OleDbConnection</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or PL/SQL command</param>  
    /// <returns>an OleDbDataReader containing the resultset generated by the command</returns>
    public static OleDbDataReader ExecuteReader(string connectionString, CommandType commandType, string commandText)
    {
        //pass through the call providing null for the set of OleDbParameters
        return ExecuteReader(connectionString, commandType, commandText, (OleDbParameter[])null);
    }

    /// <summary>
    /// Execute an OleDbCommand (that returns a resultset) against the database specified in the connection string 
    /// using the provided parameters.
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  OleDbDataReader dr = ExecuteReader(connString, CommandType.StoredProcedure, "GetOrders", new OleDbParameter("@prodid", 24));
    /// </remarks>
    /// <param name="connectionString">a valid connection string for an OleDbConnection</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or PL/SQL command</param>  
    /// <param name="commandParameters">an array of OleDbParameters used to execute the command</param>
    /// <returns>an OleDbDataReader containing the resultset generated by the command</returns>
    public static OleDbDataReader ExecuteReader(string connectionString, CommandType commandType, string commandText, params OleDbParameter[] commandParameters)
    {
        //create & open an OleDbbConnection
        OleDbConnection cn = new OleDbConnection(connectionString);
        cn.Open();

        try
        {
            //call the private overload that takes an internally owned connection in place of the connection string
            return ExecuteReader(cn, null, commandType, commandText, commandParameters, OleDbConnectionOwnership.Internal);
        }
        catch
        {
            //if we fail to return the OleDbDataReader, we neeed to close the connection ourselves
            cn.Close();
            throw;
        }
    }

    /// <summary>
    /// Execute a stored procedure via an OleDbCommand (that returns a resultset) against the database specified in 
    /// the connection string using the provided parameter values.  This method will query the database to discover the parameters for the 
    /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
    /// </summary>
    /// <remarks>
    /// This method provides no access to output parameters or the stored procedure's return value parameter.
    /// 
    /// e.g.:  
    ///  OleDbDataReader dr = ExecuteReader(connString, "GetOrders", 24, 36);
    /// </remarks>
    /// <param name="connectionString">a valid connection string for an OleDbConnection</param>
    /// <param name="spName">the name of the stored prcedure</param>
    /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
    /// <returns>an OleDbDataReader containing the resultset generated by the command</returns>
    public static OleDbDataReader ExecuteReader(string connectionString, string spName, params object[] parameterValues)
    {
        //if we got parameter values, we need to figure out where they go
        if ((parameterValues != null) && (parameterValues.Length > 0))
        {
            //pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)
            OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet(connectionString, spName);

            //assign the provided values to these parameters based on parameter order
            AssignParameterValues(commandParameters, parameterValues);

            //call the overload that takes an array of OleDbParameters
            return ExecuteReader(connectionString, CommandType.StoredProcedure, spName, commandParameters);
        }
        //otherwise we can just call the SP without params
        else
        {
            return ExecuteReader(connectionString, CommandType.StoredProcedure, spName);
        }
    }

    /// <summary>
    /// Execute an OleDbCommand (that returns a resultset and takes no parameters) against the provided OleDbConnection. 
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  OleDbDataReader dr = ExecuteReader(conn, CommandType.StoredProcedure, "GetOrders");
    /// </remarks>
    /// <param name="connection">a valid OleDbConnection</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or PL/SQL command</param>
    /// <returns>an OleDbDataReader containing the resultset generated by the command</returns>
    public static OleDbDataReader ExecuteReader(OleDbConnection connection, CommandType commandType, string commandText)
    {
        //pass through the call providing null for the set of OleDbParameters
        return ExecuteReader(connection, commandType, commandText, (OleDbParameter[])null);
    }

    /// <summary>
    /// Execute an OleDbCommand (that returns a resultset) against the specified OleDbConnection 
    /// using the provided parameters.
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  OleDbDataReader dr = ExecuteReader(conn, CommandType.StoredProcedure, "GetOrders", new OleDbParameter("@prodid", 24));
    /// </remarks>
    /// <param name="connection">a valid OleDbConnection</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or PL/SQL command</param>  
    /// <param name="commandParameters">an array of OleDbParamters used to execute the command</param>
    /// <returns>an OleDbDataReader containing the resultset generated by the command</returns>
    public static OleDbDataReader ExecuteReader(OleDbConnection connection, CommandType commandType, string commandText, params OleDbParameter[] commandParameters)
    {
        //pass through the call to the private overload using a null transaction value and an externally owned connection
        return ExecuteReader(connection, (OleDbTransaction)null, commandType, commandText, commandParameters, OleDbConnectionOwnership.External);
    }

    /// <summary>
    /// Execute a stored procedure via an OleDbCommand (that returns a resultset) against the specified OleDbConnection 
    /// using the provided parameter values.  This method will query the database to discover the parameters for the 
    /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
    /// </summary>
    /// <remarks>
    /// This method provides no access to output parameters or the stored procedure's return value parameter.
    /// 
    /// e.g.:  
    ///  OleDbDataReader dr = ExecuteReader(conn, "GetOrders", 24, 36);
    /// </remarks>
    /// <param name="connection">a valid OleDbConnection</param>
    /// <param name="spName">the name of the stored procedure</param>
    /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
    /// <returns>an OleDbDataReader containing the resultset generated by the command</returns>
    public static OleDbDataReader ExecuteReader(OleDbConnection connection, string spName, params object[] parameterValues)
    {
        //if we got parameter values, we need to figure out where they go
        if ((parameterValues != null) && (parameterValues.Length > 0))
        {
            OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet(connection.ConnectionString, spName);

            AssignParameterValues(commandParameters, parameterValues);

            return ExecuteReader(connection, CommandType.StoredProcedure, spName, commandParameters);
        }
        //otherwise we can just call the SP without params
        else
        {
            return ExecuteReader(connection, CommandType.StoredProcedure, spName);
        }
    }

    /// <summary>
    /// Execute an OleDbCommand (that returns a resultset and takes no parameters) against the provided OleDbTransaction. 
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  OleDbDataReader dr = ExecuteReader(trans, CommandType.StoredProcedure, "GetOrders");
    /// </remarks>
    /// <param name="transaction">a valid OleDbTransaction</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or PL/SQL command</param>  
    /// <returns>an OleDbDataReader containing the resultset generated by the command</returns>
    public static OleDbDataReader ExecuteReader(OleDbTransaction transaction, CommandType commandType, string commandText)
    {
        //pass through the call providing null for the set of OleDbParameters
        return ExecuteReader(transaction, commandType, commandText, (OleDbParameter[])null);
    }

    /// <summary>
    /// Execute an OleDbCommand (that returns a resultset) against the specified OleDbTransaction
    /// using the provided parameters.
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///   OleDbDataReader dr = ExecuteReader(trans, CommandType.StoredProcedure, "GetOrders", new OleDbParameter("@prodid", 24));
    /// </remarks>
    /// <param name="transaction">a valid OleDbTransaction</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or PL/SQL command</param> 
    /// <param name="commandParameters">an array of OleDbParameters used to execute the command</param>
    /// <returns>an OleDbDataReader containing the resultset generated by the command</returns>
    public static OleDbDataReader ExecuteReader(OleDbTransaction transaction, CommandType commandType, string commandText, params OleDbParameter[] commandParameters)
    {
        //pass through to private overload, indicating that the connection is owned by the caller
        return ExecuteReader(transaction.Connection, transaction, commandType, commandText, commandParameters, OleDbConnectionOwnership.External);
    }

    /// <summary>
    /// Execute a stored procedure via an OleDbCommand (that returns a resultset) against the specified
    /// OleDbTransaction using the provided parameter values.  This method will query the database to discover the parameters for the 
    /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
    /// </summary>
    /// <remarks>
    /// This method provides no access to output parameters or the stored procedure's return value parameter.
    /// 
    /// e.g.:  
    ///  OleDbDataReader dr = ExecuteReader(trans, "GetOrders", 24, 36);
    /// </remarks>
    /// <param name="transaction">a valid OleDbTransaction</param>
    /// <param name="spName">the name of the stored prcedure</param>
    /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
    /// <returns>an OleDbDataReader containing the resultset generated by the command</returns>
    public static OleDbDataReader ExecuteReader(OleDbTransaction transaction, string spName, params object[] parameterValues)
    {
        //if we got parameter values, we need to figure out where they go
        if ((parameterValues != null) && (parameterValues.Length > 0))
        {
            OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet(transaction.Connection.ConnectionString, spName);

            AssignParameterValues(commandParameters, parameterValues);

            return ExecuteReader(transaction, CommandType.StoredProcedure, spName, commandParameters);
        }
        //otherwise we can just call the SP without params
        else
        {
            return ExecuteReader(transaction, CommandType.StoredProcedure, spName);
        }
    }

    #endregion ExecuteReader

    #region ExecuteScalar

    /// <summary>
    /// Execute a OleDbCommand (that returns a 1x1 resultset and takes no parameters) against the database specified in 
    /// the connection string. 
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  int orderCount = (int)ExecuteScalar(connString, CommandType.StoredProcedure, "GetOrderCount");
    /// </remarks>
    /// <param name="connectionString">a valid connection string for a OleDbConnection</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or T-OleDb command</param>
    /// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
    public static object ExecuteScalar(string connectionString, CommandType commandType, string commandText)
    {
        //pass through the call providing null for the set of OleDbParameters
        return ExecuteScalar(connectionString, commandType, commandText, (OleDbParameter[])null);
    }

    /// <summary>
    /// Execute a OleDbCommand (that returns a 1x1 resultset) against the database specified in the connection string 
    /// using the provided parameters.
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  int orderCount = (int)ExecuteScalar(connString, CommandType.StoredProcedure, "GetOrderCount", new OleDbParameter("@prodid", 24));
    /// </remarks>
    /// <param name="connectionString">a valid connection string for a OleDbConnection</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or T-OleDb command</param>
    /// <param name="commandParameters">an array of OleDbParamters used to execute the command</param>
    /// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
    public static object ExecuteScalar(string connectionString, CommandType commandType, string commandText, params OleDbParameter[] commandParameters)
    {
        //create & open a OleDbConnection, and dispose of it after we are done.
        using (OleDbConnection cn = new OleDbConnection(connectionString))
        {
            cn.Open();

            //call the overload that takes a connection in place of the connection string
            return ExecuteScalar(cn, commandType, commandText, commandParameters);
        }
    }

    /// <summary>
    /// Execute a stored procedure via a OleDbCommand (that returns a 1x1 resultset) against the database specified in 
    /// the conneciton string using the provided parameter values.  This method will query the database to discover the parameters for the 
    /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
    /// </summary>
    /// <remarks>
    /// This method provides no access to output parameters or the stored procedure's return value parameter.
    /// 
    /// e.g.:  
    ///  int orderCount = (int)ExecuteScalar(connString, "GetOrderCount", 24, 36);
    /// </remarks>
    /// <param name="connectionString">a valid connection string for a OleDbConnection</param>
    /// <param name="spName">the name of the stored prcedure</param>
    /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
    /// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
    public static object ExecuteScalar(string connectionString, string spName, params object[] parameterValues)
    {
        //if we got parameter values, we need to figure out where they go
        if ((parameterValues != null) && (parameterValues.Length > 0))
        {
            //pull the parameters for this stored procedure from the parameter cache (or discover them & populet the cache)
            OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet(connectionString, spName);

            //assign the provided values to these parameters based on parameter order
            AssignParameterValues(commandParameters, parameterValues);

            //call the overload that takes an array of OleDbParameters
            return ExecuteScalar(connectionString, CommandType.StoredProcedure, spName, commandParameters);
        }
        //otherwise we can just call the SP without params
        else
        {
            return ExecuteScalar(connectionString, CommandType.StoredProcedure, spName);
        }
    }

    /// <summary>
    /// Execute a OleDbCommand (that returns a 1x1 resultset and takes no parameters) against the provided OleDbConnection. 
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  int orderCount = (int)ExecuteScalar(conn, CommandType.StoredProcedure, "GetOrderCount");
    /// </remarks>
    /// <param name="connection">a valid OleDbConnection</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or T-OleDb command</param>
    /// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
    public static object ExecuteScalar(OleDbConnection connection, CommandType commandType, string commandText)
    {
        //pass through the call providing null for the set of OleDbParameters
        return ExecuteScalar(connection, commandType, commandText, (OleDbParameter[])null);
    }

    /// <summary>
    /// Execute a OleDbCommand (that returns a 1x1 resultset) against the specified OleDbConnection 
    /// using the provided parameters.
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  int orderCount = (int)ExecuteScalar(conn, CommandType.StoredProcedure, "GetOrderCount", new OleDbParameter("@prodid", 24));
    /// </remarks>
    /// <param name="connection">a valid OleDbConnection</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or T-OleDb command</param>
    /// <param name="commandParameters">an array of OleDbParamters used to execute the command</param>
    /// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
    public static object ExecuteScalar(OleDbConnection connection, CommandType commandType, string commandText, params OleDbParameter[] commandParameters)
    {
        //create a command and prepare it for execution
        OleDbCommand cmd = new OleDbCommand();
        PrepareCommand(cmd, connection, (OleDbTransaction)null, commandType, commandText, commandParameters);

        //execute the command & return the results
        return cmd.ExecuteScalar();
    }

    /// <summary>
    /// Execute a stored procedure via a OleDbCommand (that returns a 1x1 resultset) against the specified OleDbConnection 
    /// using the provided parameter values.  This method will query the database to discover the parameters for the 
    /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
    /// </summary>
    /// <remarks>
    /// This method provides no access to output parameters or the stored procedure's return value parameter.
    /// 
    /// e.g.:  
    ///  int orderCount = (int)ExecuteScalar(conn, "GetOrderCount", 24, 36);
    /// </remarks>
    /// <param name="connection">a valid OleDbConnection</param>
    /// <param name="spName">the name of the stored prcedure</param>
    /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
    /// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
    public static object ExecuteScalar(OleDbConnection connection, string spName, params object[] parameterValues)
    {
        //if we got parameter values, we need to figure out where they go
        if ((parameterValues != null) && (parameterValues.Length > 0))
        {
            //pull the parameters for this stored procedure from the parameter cache (or discover them & populet the cache)
            OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet(connection.ConnectionString, spName);

            //assign the provided values to these parameters based on parameter order
            AssignParameterValues(commandParameters, parameterValues);

            //call the overload that takes an array of OleDbParameters
            return ExecuteScalar(connection, CommandType.StoredProcedure, spName, commandParameters);
        }
        //otherwise we can just call the SP without params
        else
        {
            return ExecuteScalar(connection, CommandType.StoredProcedure, spName);
        }
    }

    /// <summary>
    /// Execute a OleDbCommand (that returns a 1x1 resultset and takes no parameters) against the provided OleDbTransaction. 
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  int orderCount = (int)ExecuteScalar(trans, CommandType.StoredProcedure, "GetOrderCount");
    /// </remarks>
    /// <param name="transaction">a valid OleDbTransaction</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or T-OleDb command</param>
    /// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
    public static object ExecuteScalar(OleDbTransaction transaction, CommandType commandType, string commandText)
    {
        //pass through the call providing null for the set of OleDbParameters
        return ExecuteScalar(transaction, commandType, commandText, (OleDbParameter[])null);
    }

    /// <summary>
    /// Execute a OleDbCommand (that returns a 1x1 resultset) against the specified OleDbTransaction
    /// using the provided parameters.
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  int orderCount = (int)ExecuteScalar(trans, CommandType.StoredProcedure, "GetOrderCount", new OleDbParameter("@prodid", 24));
    /// </remarks>
    /// <param name="transaction">a valid OleDbTransaction</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or T-OleDb command</param>
    /// <param name="commandParameters">an array of OleDbParamters used to execute the command</param>
    /// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
    public static object ExecuteScalar(OleDbTransaction transaction, CommandType commandType, string commandText, params OleDbParameter[] commandParameters)
    {
        //create a command and prepare it for execution
        OleDbCommand cmd = new OleDbCommand();
        PrepareCommand(cmd, transaction.Connection, transaction, commandType, commandText, commandParameters);

        //execute the command & return the results
        return cmd.ExecuteScalar();

    }

    /// <summary>
    /// Execute a stored procedure via a OleDbCommand (that returns a 1x1 resultset) against the specified
    /// OleDbTransaction using the provided parameter values.  This method will query the database to discover the parameters for the 
    /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
    /// </summary>
    /// <remarks>
    /// This method provides no access to output parameters or the stored procedure's return value parameter.
    /// 
    /// e.g.:  
    ///  int orderCount = (int)ExecuteScalar(trans, "GetOrderCount", 24, 36);
    /// </remarks>
    /// <param name="transaction">a valid OleDbTransaction</param>
    /// <param name="spName">the name of the stored prcedure</param>
    /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
    /// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
    public static object ExecuteScalar(OleDbTransaction transaction, string spName, params object[] parameterValues)
    {
        //if we got parameter values, we need to figure out where they go
        if ((parameterValues != null) && (parameterValues.Length > 0))
        {
            //pull the parameters for this stored procedure from the parameter cache (or discover them & populet the cache)
            OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet(transaction.Connection.ConnectionString, spName);

            //assign the provided values to these parameters based on parameter order
            AssignParameterValues(commandParameters, parameterValues);

            //call the overload that takes an array of OleDbParameters
            return ExecuteScalar(transaction, CommandType.StoredProcedure, spName, commandParameters);
        }
        //otherwise we can just call the SP without params
        else
        {
            return ExecuteScalar(transaction, CommandType.StoredProcedure, spName);
        }
    }

    #endregion ExecuteScalar
}

	/// <summary>
	/// OleDbHelperParameterCache provides functions to leverage a static cache of procedure parameters, and the
	/// ability to discover parameters for stored procedures at run-time.
	/// </summary>
public sealed class OleDbHelperParameterCache
{
    #region private methods, variables, and constructors

    //Since this class provides only static methods, make the default constructor private to prevent 
    //instances from being created with "new OleDbHelperParameterCache()".
    private OleDbHelperParameterCache() { }

    private static Hashtable paramCache = Hashtable.Synchronized(new Hashtable());

    /// <summary>
    /// resolve at run-time the appropriate set of OleDbParameters for a stored procedure
    /// </summary>
    /// <param name="connectionString">a valid connection string for a OleDbConnection</param>
    /// <param name="spName">the name of the stored prcedure</param>
    /// <param name="includeReturnValueParameter">weather or not to onclude ther return value parameter</param>
    /// <returns></returns>
    private static OleDbParameter[] DiscoverSpParameterSet(string connectionString, string spName, bool includeReturnValueParameter)
    {
        using (OleDbConnection cn = new OleDbConnection(connectionString))
        using (OleDbCommand cmd = new OleDbCommand(spName, cn))
        {
            cn.Open();
            cmd.CommandType = CommandType.StoredProcedure;

            OleDbCommandBuilder.DeriveParameters(cmd);

            if (!includeReturnValueParameter)
            {
                if (ParameterDirection.ReturnValue == cmd.Parameters[0].Direction)
                    cmd.Parameters.RemoveAt(0);
            }

            OleDbParameter[] discoveredParameters = new OleDbParameter[cmd.Parameters.Count];

            cmd.Parameters.CopyTo(discoveredParameters, 0);

            return discoveredParameters;
        }
    }

    //deep copy of cached OleDbParameter array
    private static OleDbParameter[] CloneParameters(OleDbParameter[] originalParameters)
    {
        OleDbParameter[] clonedParameters = new OleDbParameter[originalParameters.Length];

        for (int i = 0, j = originalParameters.Length; i < j; i++)
        {
            clonedParameters[i] = (OleDbParameter)((ICloneable)originalParameters[i]).Clone();
        }

        return clonedParameters;
    }

    #endregion private methods, variables, and constructors

    #region caching functions

    /// <summary>
    /// add parameter array to the cache
    /// </summary>
    /// <param name="connectionString">a valid connection string for an OleDbConnection</param>
    /// <param name="commandText">the stored procedure name or T-OleDb command</param>
    /// <param name="commandParameters">an array of OleDbParamters to be cached</param>
    public static void CacheParameterSet(string connectionString, string commandText, params OleDbParameter[] commandParameters)
    {
        string hashKey = connectionString + ":" + commandText;

        paramCache[hashKey] = commandParameters;
    }

    /// <summary>
    /// retrieve a parameter array from the cache
    /// </summary>
    /// <param name="connectionString">a valid connection string for a OleDbConnection</param>
    /// <param name="commandText">the stored procedure name or T-OleDb command</param>
    /// <returns>an array of OleDbParameters</returns>
    public static OleDbParameter[] GetCachedParameterSet(string connectionString, string commandText)
    {
        string hashKey = connectionString + ":" + commandText;

        OleDbParameter[] cachedParameters = (OleDbParameter[])paramCache[hashKey];

        if (cachedParameters == null)
        {
            return null;
        }
        else
        {
            return CloneParameters(cachedParameters);
        }
    }

    #endregion caching functions

    #region Parameter Discovery Functions

    /// <summary>
    /// Retrieves the set of OleDbParameters appropriate for the stored procedure
    /// </summary>
    /// <remarks>
    /// This method will query the database for this information, and then store it in a cache for future requests.
    /// </remarks>
    /// <param name="connectionString">a valid connection string for a OleDbConnection</param>
    /// <param name="spName">the name of the stored prcedure</param>
    /// <returns>an array of OleDbParameters</returns>
    public static OleDbParameter[] GetSpParameterSet(string connectionString, string spName)
    {
        return GetSpParameterSet(connectionString, spName, true);
    }

    /// <summary>
    /// Retrieves the set of OleDbParameters appropriate for the stored procedure
    /// </summary>
    /// <remarks>
    /// This method will query the database for this information, and then store it in a cache for future requests.
    /// </remarks>
    /// <param name="connectionString">a valid connection string for an OleDbConnection</param>
    /// <param name="spName">the name of the stored procedure</param>
    /// <param name="includeReturnValueParameter">a bool value indicating weather the return value parameter should be included in the results</param>
    /// <returns>an array of OleDbParameters</returns>
    public static OleDbParameter[] GetSpParameterSet(string connectionString, string spName, bool includeReturnValueParameter)
    {
        string hashKey = connectionString + ":" + spName + (includeReturnValueParameter ? ":include ReturnValue Parameter" : "");

        OleDbParameter[] cachedParameters;

        cachedParameters = (OleDbParameter[])paramCache[hashKey];

        if (cachedParameters == null)
        {
            cachedParameters = (OleDbParameter[])(paramCache[hashKey] = DiscoverSpParameterSet(connectionString, spName, includeReturnValueParameter));
        }

        return CloneParameters(cachedParameters);
    }

    #endregion Parameter Discovery Functions

}